1. Field of the Invention
The present invention relates to a semiconductor process. More particularly, the present invention relates to a method of fabricating an interconnection in an insulating layer on a wafer and a structure thereof.
2. Description of the Related Art
Integrated circuit fabrication is a high-tech industry that involves four major subsystems including integrated circuit design, wafer manufacturing, wafer testing and wafer packaging. After all the steps necessary for fabricating a complete integrated circuit have been completed, a series of tests is carried out to ensure the quality of the final products and/or to modify the circuit fabrication process according to the test results. Furthermore, at the end of a wafer fabrication cycle, the wafer frequency undergoes many types of wafer tests. If defects or out-of-spec elements are found in the circuit on the wafer, a repair operation is often carried out to form a repair circuit. This kind of operational mode not only saves the trouble of producing rework photomask and some other costs, but also significantly increases overall yield of the wafer.
In 1988, Intel's researcher Richard Leven-good uses a focused ion beam (FIB) device to ‘deposit’ a section of absent circuit on a microprocessor chip. Thereafter, the chip is tested and found to operate normally. From that time on, FIB has become one of the principal techniques for repairing defective circuits or out-of-spec circuits of a silicon wafer. However, there are a still a few drawbacks in using the FIB technique to repair wafer circuits. Because a FIB device is an expensive piece of equipment, using the FIB technique to repair circuits on the wafer separated by a long distance is rather expensive. Furthermore, it takes considerable time to repair each stretch of circuit using the FIB technique. The repairing time is even longer if the circuits to be repaired are separated by a long distance.